phasors.rb

require 'rational'
require 'complex'

class Phasor
  attr_reader :magnitude, :angle

  class << self
    def from_polar(magnitude, angle)
      new(magnitude, angle)
    end

    def from_complex(c)
      magnitude, angle_in_radians = c.polar
      new(magnitude, radians_to_degrees(angle_in_radians))
    end

    def degrees_to_radians(degrees)
      (degrees / 180.0) * Math::PI
    end

    def radians_to_degrees(radians)
      (radians * 180.0) / Math::PI
    end
  end

  def initialize(magnitude, angle)
    @magnitude = magnitude
    @angle     = angle % 360

    if @angle > 180
      @angle -= 360
    end
  end

  def to_c
    Complex.polar(@magnitude, self.class.degrees_to_radians(@angle))
  end

  def +(other)
    self.class.from_complex(to_c + other.to_c)
  end

  def *(other)
    self.class.from_polar(magnitude * other.magnitude, angle + other.angle)
  end

  def /(other)
    self.class.from_polar(magnitude.to_f / other.magnitude, angle - other.angle)
  end

  def to_s_polar
    "#{magnitude.round(2)}<#{angle.round(2)}∘"
  end

  def to_s_complex
    c = to_c
    c = Complex(c.real.round(2), c.imaginary.round(2))
    c.to_s
  end
end

p1 = Phasor.new(4, 30)
p2 = Phasor.new(3, 20)

puts "sum"
puts (p1 + p2).to_s_polar
puts (p1 + p2).to_s_complex
puts

puts "product"
puts (p1 * p2).to_s_polar
puts (p1 * p2).to_s_complex
puts

puts "division"
puts (p1 / p2).to_s_polar
puts (p1 / p2).to_s_complex
puts